Ship comprising one or more derricks such as a dredge with suction pipe derricks

ABSTRACT

The invention relates to a ship (1) with one or more derricks (4), in particular a dredge having at least one derrick (4) for handling the suction pipe (22) which derrick (4) can be moved between an inboard position (7) and a vertical position. The derrick has guiding tracks (8,9) for a crane jib (17) which tracks (8,9) in the vertical position of the derrick (4) are in line with guiding tracks (15,16) inside the profile of the side wall (3) of the ship. The cable for controlling the jib (17) is protected by a channel inside the profile of the ship side wall (3) between the latter guiding tracks (15,16). The guiding tracks (8,9,15,16) have upper and lower stops (29,28) for controlling the movements of the crane jib (17) which jib (17) is pivotable about a horizontal axis (18) between a position perpendicular to the derrick (4) and a downwardly directed position.

BACKGROUND OF THE INVENTION

The invention relates to a ship comprising one or more derrickspositioned on deck along the side of the ship, which derricks havepush-pull-mechanism, such as a cylinder, for swinging the respectivederrick around a horizontal axis from an inboard position to a positionin which a load can be lowered outboard and vice versa, such as thederrick for the suction pipe of a dredge, which derrick cooperates witha winch of which the hoisting cable runs over one or more pulleys to aload carrying hoist block such that said hoist block is situatedoutboard in the working position of said derrick. Such a ship iscommonly known. The derrick of a ship of this type can swivel between anoblique inwards directed resting position and an oblique outwardsdirected working position in which a load outboard at a distance of theship's hull can be handled.

If the load is embodied as a suction pipe used for carrying out dredgingoperations, then it is often necessary to lower said pipe to aconsiderable depth under water whereby, especially in troublesomecurrents or high seas, the danger exists that the hoisting cables andthe load hanging thereon such as the suction pipe can come into conflictwith the ship's hull. Furthermore the danger exists that the hoistingcables are damaged by bodies floating in or on the water such as icefloes.

An object of the invention is now to provide a ship comprising one ormore derricks, especially a ship comprising derricks for handling asuction pipe, whereby the danger of damaging the hoisting cables iseliminated and furthermore it is prevented that the load will come intoconflict with the ship's hull.

SUMMARY OF THE INVENTION

According to the invention that object is primarily reached in that saidderrick comprises at the outboard directed side guiding tracks for asliding piece carrying a crane jib, and the hull of said ship comprisesinwards of the shell also guiding tracks running over the total heightof the ship's side wall, which guiding tracks of said derrick are in theworking position of said derrick aligned with and connected to theguiding tracks on the ships hull, whereby between or besides saidguiding tracks of the derrick and the ship a channel C for a hoistingcable connected to said sliding piece is installed in the ship side wallarea inside the ship's hull.

With this embodiment of ship and derrick it is attained that the loadsuspended from the crane jib during the upwards or downwards movement ofsaid sliding piece carrying said crane jib, always is kept at a fixeddistance from the ships hull. Furthermore it is attained that the cablesare situated in a channel C inwards of the shell of said hull, so thatthere is no chance that said cable is damaged by ice floes. It is alsopossible that said sliding piece with said crane jib is moved by meansof a separate hoisting cable and corresponding winch over said guidingtracks of the derrick and the ship's hull, in which case the hoist blockcarried by said crane jib has a separate hoisting cable running overguiding pulleys and through the channel and over said derrick to aseparate corresponding winch. Said guiding tracks can have stop meansnear the upper end of said derrick and near the under side of the sidewall of the ship's hull, which stop elements are generally useful buthave a special meaning when, according to the invention, the crane jibis pivotably connected to said sliding piece by means of a horizontalshaft, directed essentially parallel to the longitudinal direction ofthe ship, which sliding piece has a stop element restricting the upwardmovement of said crane jib around said horizontal shaft, whereby thehoisting cable runs over a top pulley, through said channel and over aguiding pulley of said sliding piece, which guiding pulley extends intosaid channel towards said hoist block and runs back to a fixed point onsaid sliding piece, whereby said hoist block is supported in an outwardsopen bifurcated part of said crane jib, whereby the supporting point ispositioned above the pivot shaft of said crane jib in the situation inwhich said crane jib is arrested by said stop element.

Thereby it is attained that the crane jib during lowering of said cranejib carrying sliding piece is maintained in an outwards directedhorizontal position arrested against the stop element of said slidingpiece, until said sliding piece has reached the lower stop means. Whenthe load cable runs out further, than the crane jib swivels around thehorizontal axis to the downwards directed position in which the hoistblock is able to leave the bifurcated crane jib part so that the load,for instance the suction pipe can be lowered further.

During raising of the load said hoist block is received into saidbifurcated crane jib part, after which the crane jib swivels upwards asa result of the lever action between the supporting point in saidbifurcated part and the horizontal shaft of the crane jib, until thecrane jib is arrested in the horizontal position against the stopelement in the sliding piece whereafter, during further raising of theload, also said sliding piece carrying said crane jib will move upwards.Said movement is continued until the sliding piece is arrested by theupper stop means near the end of the derrick. In this position a lockingdevice can be activated, after which the hoisting winch can be switchedoff. Using a double active cylinder the derrick can be turned over tothe inboard position and by running out the hoisting cable said cranejib may be swiveled into a position in which the thereon hanging suctionpipe is lowered into a supporting saddle.

When the suction pipe has to be brought out again, then the hoistingcable is turned in, the crane jib raises the suction pipe from thesupporting saddle until said crane jib is arrested against the stopelement, after which the derrick is turned over outwards to the verticalposition.

THE DRAWINGS

The invention will now be explained in more detail with reference to theattached drawings.

FIG. 1 illustrates a transverse sectional view of part of a shipcarrying the derrick shown in several positions.

FIG. 2 illustrates a side view of the ship in FIG. 1 wherein the hoistblock is in the lowest position.

FIG. 3 shows a sectional view according to the line III--III in FIG. 2.

DETAILED DESCRIPTION

FIG. 1 shows part of the ship 1 comprising a deck 2 and a side wall 3. Anumber of derricks 4 are installed on the deck, one of which isillustrated in FIGS. 1 and 2. Said derrick is at 5 pivotably connectedto the ships deck and can be moved by means of a pressure cylinder 6between the inboard position 7 illustrated by means of dash and dotlines and the working position illustrated with full lines. Said derrickcarries guiding tracks 8 and 9, in which a sliding piece 10 is guided bymeans of sidewards extending sliding blocks 11, 12, 13 and 14.

Further guiding tracks 15 and 16 are installed in the side wall of theship's hull, which guiding tracks are positioned inwards of the ship'sshell as is illustrated in FIG. 3. Said guiding tracks 15 and 16 arealigned with the guiding tracks 8 and 9 of the derrick 4 when saidderrick is in the erected vertical working position. In that case it ispossible for said sliding piece 10 to be transfered from the guidingtracks 8 and 9 into the guiding tracks 15 and 16.

The sliding piece 10 carries a crane jib 17 which is at 18 pivotablyconnected by means of a universal joint having a horizontal axis 18 andperpendicular thereto a further axis 19.

The end of the crane jib is embodied as a bifurcated part denoted with20, in which the hoist block 21 is supported comprising means forcarrying the load 22, which in the illustrated example is embodied as asuction pipe.

On deck a winch 23 is installed the cable of which runs over the toppulley 24 of the derrick, over the guiding pulley 25 of the slidingpiece 10, from there to the pulley 26 of the hoist block 21 and furtherto a fixed point 27 onto said sliding piece.

The guiding tracks 15 and 16 have a stop element 28 at their lower endand the guiding tracks 8 and 9 have a stop element 29 at their upperend.

The crane jib 17 is in the outwards swiveled position illustrated in theupper part of FIG. 1, arrested by stop means 30 in said sliding piecerestricting the upwards movement, which stop means 30 are embodied suchthat they also restrict sideward movements around the pivot shaft 19 ofthe universal joint.

The derrick 4 has a supporting yoke or saddle 31 for the suction pipe22.

In the upper section of the derrick a locking element 32 is installedwhich is able to reach under the cross beam of the sliding piece 10, andwhich locking element 32 can rotate around the shaft 33 and can beoperated by means of the air pressure cylinder 34.

Starting from the resting position, illustrated with dots and dash linesin the left hand side of FIG. 1, in which the suction pipe 22 rests inthe supporting saddle 31, reeling in the hoisting cable of the winch 23will result in raising the suction pipe 22 from the saddle 31, whereuponthe crane jib will swivel from the position 17' to the position 17"until said jib is arrested by the stop element 30 on the sliding piece.

Thereafter the derrick is brought into the vertical position by means ofthe cylinder 6 and when the hoisting cable is kept short then it ispossible to pull the locking device 32 using the cylinder 34, whereafterby means of the winch the sliding piece can be moved downwards throughthe guiding tracks 8 and 9, whilst the crane jib is maintained in thehorizontal position as illustrated in the upper right part of FIG. 1.The reason for this is, that the crane jib carrying the load ismaintained against the stop element of the sliding piece by two sectionsof the hoist cable. The pulling force acting on the crane jib istherefore approximately twice the total force in the hoisting cable,whereas only once the total force in the hoisting cable is equal to theforce necessary to move said sliding piece, crane jib and load downwardsor upwards.

When said sliding piece is lowered further then it will be transferredfrom the guiding tracks 8 and 9 into the guiding tracks 15 and 16, untilthe lowest position illustrated with full lines in FIG. 1 is reached. Inthis position the sliding piece is arrested against the stop element 28.

During the whole of this movement and during maintaining of the lowestposition the hoisting cable is protected between said guiding tracks 15and 16 so that said cable cannot be damaged by bodies floating in thewater.

As soon as the sliding piece is arrested against the stop element 28further paying out of the hoisting cable will result in a downwardsswiveling movement of the crane jib to the position which with fulllines is illustrated in FIGS. 1 and 2. If, after reaching this situationthe hoisting cable is further payed out, then the hoist block 21 willleave the fork 20 and will move downwards as is illustrated with thedash and dot lines in the lower half of FIG. 1.

During said downwards swiveling movement the hoisting cable is guided byan additional guiding pulley 35.

In said downwards directed position the crane jib is also arrestedagainst the stop element 28, but as result of the installation of auniversal joint 18, 19 said crane jib is able to follow all themovements of the hoisting cable and the load as is illustrated in thelower part of FIG. 2 by the dash and dot lines.

Because the fork 20 of the crane jib 17 is shifted in relation to thepivot shaft 18, that means that in the transversely outwards directedposition illustrated in the upper right part of FIG. 1 said fork ispositioned above said pivot joint, there is a lever acting between theend of said crane jib and said pivot joint 18 which assures, that duringraising of the load said crane jib will swivel from the verticalposition back upwards into the horizontal position. During the returnmovement the sliding piece moves with the crane jib in the horizontalposition upwards until it is arrested against the stop element 29 afterwhich it is fixed by means of the locking device.

After moving the derrick 4 back to the inboard position 7, paying out ofthe hoisting cable will result in bringing the crane jib into position17', in which the pipe 22 will come to rest on the supporting saddle 31.

Instead of only one hoisting cable for carrying out all the describedmovements, also an embodiment, in which a separate cable withcorresponding winch is used as hoisting cable for the load and anotherseparate cable with corresponding winch is used for moving the slidingpiece, falls within the scope of the invention.

In said single hoisting cable or in said separate load cable a swellcompensator can be installed.

I claim:
 1. In a ship having a derrick on deck along a side of the shipto handle the suction tube of a dredge, means mounting the derrick forvertical swinging movement about a horizontal axis from an inboardposition toward a position in which the suction tube can be loweredoutboard and vice versa, means for swinging the derrick about saidhorizontal axis, a hoisting winch having a hoisting cable, a hoist blockfor carrying the suction tube, said hoist block being disposed outboardin the latter said position of said derrick, pulleys about which saidcable extends to said hoist block, guiding tracks on said derrick,guiding tracks on the hull of the ship, and a sliding piece slidablealong the guiding tracks on said derrick and on said ship between anupper position on the guiding tracks of said derrick and a lowerposition on the guiding tracks of said ship; the improvement comprisinga crane jib on said sliding piece having an outer end carrying saidhoisting block, said guiding tracks on the hull of the ship beingdisposed within the profile of the side wall of the ship, and said cablehaving a portion disposed between the guiding tracks of the derrick andbetween the guiding tracks of the ship inwardly of the profile of saidside wall of the ship when said sliding piece is in said lower position.2. Ship according to claim 1, in which said guiding tracks have stopmeans near the upper end of the derrick and near the under side of theside wall of the ships hull.
 3. Ship according to claim 2, in which inthe upper end of said derrick near said stop means an on and offswitchable locking device for the sliding piece is installed.
 4. Shipaccording to claim 1, in which the crane jib is pivotably connected tosaid sliding piece by means of a horizontal shaft, directed essentiallyparallel to the length direction of the ship, which sliding piece has astop element restricting the upwards movement of said crane jib aroundsaid horizontal shaft, whereby the hoist cable runs over a top pulley onsaid derrick, between said guide tracks and over a guiding pulley ofsaid sliding piece, which guiding pulley extends between said guidingtracks, to said hoist block and runs back to a fixed point on saidsliding piece, whereby said hoist block is supported in an outwards openbifurcated part of said crane jib, whereby the supporting point ispositioned above the pivot shaft of said crane jib, in the situation inwhich said crane jib is arrested by said stop element.
 5. Ship accordingto claim 4, in which said crane jib is connected to said sliding pieceby means of a universal joint, and said sliding piece comprisessidewards acting stop elements for restricting the transverse movementof said crane jib around said universal joint in the situation in whichsaid crane jib is arrested by said sliding piece stop element whichrestricts the upward movement.
 6. A ship according to claim 1, in whichsaid guiding tracks on the ship are straight and vertical.
 7. A shipaccording to claim 1, in which the ship is elongated and said horizontalaxis extends parallel to the length of the ship.
 8. A ship according toclaim 1, and means mounting said crane jib on said sliding piece forvertical swinging movement about a horizontal axis disposed parallel tothe first-mentioned horizontal axis.